1. Field of the Invention
The present invention relates to a fluid injection pump. In particular, the present invention relates to a fluid injection pump that is capable of pumping multiple fluids at predetermined volumes. The present invention further relates to a fluid injection pump used in a rotary-die encapsulation process for filling softgel capsules with multiple fluids.
2. Description of the Related Technology
Softgel capsules are commonly produced by a rotary-die process, which was described in detail in Ebert, W. R., “Soft elastic gelatin capsules: a unique dosage form,” Pharmaceutical Tech., Oct. 1977; Stanley, J. P., “Soft Gelatin Capsules,” in The Theory and Practice of Industrial Pharmacy (Lachman, Lieberman and Kanig, Editors), 3rd Edition, published by Lea & Febiger; and U.S. Pat. Nos. 1,970,396, 2,288,327, and 2,318,718, the teachings of all of which are incorporated herein by reference in their entireties. Briefly, during a typical rotary-die process, two softgel bands, generated from an aqueous gelatin solution, are guided towards counter-rotating forming rolls of an encapsulation machine. On their surfaces, these forming rolls have recesses (cavities) that are encircled by flanges. The two bands are heated to a suitable temperature that is below their melting point and fused to each other to form capsules under the force of the flanges. The capsules thereby being formed are dosed with a filling material through fine channels in a filling wedge of the encapsulation machine. The dosed capsules are then severed from the bands by being pinched off between the flanges.
The dosing of the filling material into the softgel capsules is performed with the aid of precision dosing pumps (syringe-type dosing pumps), which are in the same generic category as reciprocating displacement machines. The metered volume of filling material is delivered by the pumps to the capsules through the filling wedge in one or more pulses, depending on the volume of the capsules. The capsules created are made to bulge to the extent to which a pumping surge forces filling material into the capsules. Although this pumping principle was described as early as 1935, the designs of the pumps and of the filling wedges have remained substantially unchanged to the present day.
One typical pump 4 used in a conventional rotary-die process is illustrated in FIG. 1. The filling material (a fluid) is stored in a tank 1. The pump 4 has multiple pairs of syringes 3 with each pair operating reciprocally (i.e., the two plungers of each pair of syringes sliding reciprocally to each other) to pump the filling material through tubes 5 to the filling wedge. Each syringe 3 delivers a metered volume of filling material into a tube 5, which passes the filling material to a capsule. The filling wedge comprises a distributor 6 for distributing the filling material to the proper wedge orifices, a diverting valve mechanism 7 for controlling the supply of the filling material by allowing the filling material to flow to the wedge, or diverting it back to the tank 1, a tube assembly plate 8 on which pipes for connection with the plurality of tubes 5 are provided upright, and a nozzle segment 2 integrated into the filling wedge. The nozzle segment 2 supplies the filling material to the capsules. Further, at least one return tube 9 is interposed between the distributor 6, the diverting valve mechanism 7, and the tank 1, for returning the unused filling material back to the tank 1. This pump 4, though having multiple pairs of syringes 3, can pump only one filling material from the same tank 1 to the wedge to be filled into capsules.
There are a few pumps developed recently with improved functionalities for softgel encapsulation. US 2014/035388 discloses a pumping system for filling softgel capsules with an electromagnetic actuation mechanism. The pumping system includes a container for storing therapeutic or non-therapeutic compositions, a low-pressure pump, a high-pressure pump, a supply line for the therapeutic or non-therapeutic compositions, and one or more nozzles/injectors to fill the softgel capsules with the therapeutic or non-therapeutic compositions. The pumping system also has a dose-measuring device including an electromagnetic coil, a housing with an outlet passage, and a connector part defining an inlet passage connected to the container. The housing forms an internal chamber that is in fluid communication with the inlet passage and the outlet passage. A piston is moveably arranged in the internal chamber of the housing for reciprocating motion, where the housing has a ferromagnetic actuation part for electromagnetic actuation of the piston by the electromagnetic coil.
U.S. Pat. No. 8,651,840 discloses a syringe pump for making softgel capsules. The pump includes a switch body and a syringe body that form an accommodation space. The switch body has liquid suction and injection holes, both communicative with the accommodation space. The syringe body has a channel for receiving a plunger rod, and a rotary switch closely press-fit to the switch body to form a hermetic surface. The plunger rod linearly reciprocates in the channel so that the accommodation space periodically reaches maximum and minimum values of capacity. The structure of the rotary switch shifts between opening and closing states of the liquid suction and injection holes, which is substantially free of leakage of filling material. There is minimal mixing and dissolving of the filling material with lubricating oil during normal operation of the syringe pump, thereby enhancing the precision in the loading amount and eliminating contamination of the filling material by the lubricating oil.
These improved pumps still have one common drawback, i.e., the limitation of pumping only one fluid to the wedge to be injected into softgel capsules. They are not suitable for delivering multiple fluids at predetermined volumes to the same capsules.
There are several pumps that are capable of delivering multiple fluids. For example, U.S. Pat. No. 8,951,023 discloses a pumping system for delivering a plurality of different fluids serially to a location at substantially the same flow rate. The pumping system includes a plurality of diaphragm pumps, with each capable of handling a different fluid. The pumping system also has a plurality of outlets, with each outlet being connected to the port of a respective diaphragm pump, and a sensor for detecting the pressure of the fluid in the chamber of a diaphragm pump. The diaphragm pumps may each operate under different pressure to accommodate fluids with different viscosities, thus ensuring a desirable flow rate for each fluid.
US 2010/0111721 discloses a dual piston-pump apparatus comprising a pump chassis assembly having a pair of spaced-apart, elongated piston bores, a lead screw shaft having a motor driven end and another portion thereof rotatably mounted to said chassis assembly for rotation about a screw rotational axis, and a piston drive member threadably cooperating with the lead screw shaft for reciprocating movement longitudinally along the screw rotational axis thereof between a first position and a second position. The drive member has a pair of spaced-apart piston shafts, each piston shaft having a respective piston head portion slideably received in a respective piston bore of the chassis assembly between a dispensing condition and an aspiration condition as the drive member is driven along the lead screw shaft between the first position and the second position, respectively. The pump apparatus also has an anti-rotation device cooperating between the pump chassis assembly and a drive member to substantially prevent rotational displacement of the drive member relative to the pump chassis assembly.
U.S. Pat. No. 4,381,180 discloses a double-acting, double-diaphragm pump suitable for pumping two fluids. The pump includes adjustable disk members mounted on a reciprocable rod connecting and actuating the diaphragms. These disks alternately engage an extending shaft of a pilot valve to move the valve and redirect the flow of pressurized fluid therethrough. The pressurized fluid behind the diaphragm is pressed to flow to a slide valve. The slide valve is cycled by the pilot valves as the disks on the reciprocated rod engage the pilot valves. Each pump half has the exterior wall member disposed to carry two one-way valves, one valve to inhibit inward flow to the chamber and one valve to inhibit flow from the chamber.
U.S. Pat. No. 4,563,175 discloses a multiple syringe pump, comprising a pump housing, two or more seating recesses therein to receive two or more syringes for delivering two or more different substances to a patient intravenously, such as nutritional elements in one fluid and medication substances in another fluid. The pump also has a corresponding plurality of drive mechanisms in the pump housing powered by an electrical source with connections to each of the two or more syringes seated in the pump housing to move the syringe plungers at a controlled rate to fill and discharge the syringes. The drive mechanisms are operable and controllable separately, for operation at different rates of speed and to independently control rates of discharge of each of the syringes. The discharge ports of the syringes are connected to respective discharge tubes which in turn lead to a Y-connector that has a common outlet port connected to a single tube leading to a patient for intravenous infusion of the respective substances.
However, these pumps, though capable of continuously pumping two or more fluids, are not suitable for delivering these fluids at predetermined volumes, thus are not suitable for applications such as an encapsulation process for producing softgel capsules.